(1) Field of the Invention
The present invention relates to a continuous dispersing apparatus for mixing, finely grinding and dispersing a material to be processed.
(2) Background Information
As an apparatus for mixing, finely grinding and dispersing material to be processed, roll mills have been generally employed. A triple roll mill, which has been conventionally used as a roll mill, has a set of three rolls. The material is placed between a back roll and a middle roll and mixed by rotating both rolls. A front roll is positioned adjacent to the middle roll and the treated material is transferred from the middle roll to the front roll. The treated material is then scraped off and collected at the front roll.
According to the roll mill method, the material to be processed is dispersed by subjecting it to compressing-shearing-expanding actions through gaps or nips between the back and middle rolls and between the middle and front rolls. The compressing-shearing-expanding actions by means of the roll mill are conducted only at straight sections between two nips among the three rolls and thus the dispersion efficiency of these actions is low.
When the material to be processed is a high viscosity substance, if the gap between the rolls is very small at the beginning of the operation, the start of the rolls is difficult and metal parts may come into contact with each other and cause seizing, and the like.
In addition, since a conventional roll mill is of the batch type, it can not be operated continuously. A conventional roll mill is also generally open to the atmosphere allowing for the release of solvent vapor, etc. Further, the material is cooled only from the inside of the roll, and therefore can not be cooled efficiently.
Another known apparatus is a wet-type medium dispersing apparatus in which grinding elements such as balls, beads, etc. are stirred with a material to be processed in a vessel and shearing forces are applied to the material to be processed to disperse the material. However, the use of such grinding elements has the drawback that fragments or pieces of the grinding elements are often intermixed with the processed material discharged from the apparatus. Also, the structure of the apparatus is complex, and the processing is often difficult.